i. Internal Cavities
Internal body cavities (e.g., cavities within the body accessible through a body orifice or via image guided laparoscopic methods) contain organs that when diseased may benefit from prolonged topical exposure to certain drugs. These cavities are naturally wet and are either continuously flushed or generate a flow of body fluids, such as urine, serous fluids or lymphatic fluids—that contribute to gradual expelling of treatment materials.
Many cavities are characterized by their internal natural movement—due, for example, to body motion or peristaltic motion—that constantly changes their shape.
The tissue in all internal cavities in the body is composed of only three basic types of tissue: epithelial, connective and muscular. Almost all epithelial cells, rest on connective tissue, the lamina propria, which support the epithelium and provides nutrition and binds to neighboring structures. The common types of covering epithelia can have either simple, pseudo-stratified or stratified cell structure. The epithelia of vessels and serous cavities are squamous, but many other cavities have epithelia cell structure that is either cuboidal or columnar, which provide good mechanical protection and good ability to achieve adhesion. The mouth, esophagus, larynx, vagina and anal canal have a non-keratinized cell structure to maintain wetness and are more challenging for adhesion, The urinary tract has similar, but transitional cell structure, that provides stretching, mechanical strength and strongest resistance to adhesion of materials.
Several common tissue properties affect the requirements for targeted delivery materials:                wetness of the cavity lining tissue        mechanical composition and consistency        absorption capability        expansion and movement characteristics of the internal cavities or attached organs        existence of body fluids for expelling the delivery materials        
ii. Topical Treatment of Diseases
The method by which a drug is delivered can have a significant effect on its efficacy. In many cases, the drug is introduced into the blood system, which then delivers it via the blood stream throughout the body. This form of access is broadly termed systemic treatment. In other cases, a more targeted delivery can focus the therapeutic effect onto the target organ, providing therapeutic benefits and avoiding side effects. Some drugs have an optimum concentration range within which maximum benefit is derived, and concentrations above or below this range can be toxic or produce no therapeutic benefit at all. In the context of the present invention, treatments that effect specific tissues or organs by directly accessing them are termed topical treatments, as opposed to systemic treatments that were described above. Sustained release of a drug involves polymers that typically release the drug at a controlled rate due to diffusion out of the polymer or by dilution of the polymer over time. Topical administration of drugs changes the rate at which drugs enter the tissue and the pharmacokinetics of the drug, thus the correctly designed materials can optimize the therapeutic effect by controlling the drug release rate. Since all internal organ tissue is water-based, administering drugs in water-based solutions is optimal.
iii. Topically Administered Drugs
Among the drugs that can be administered topically are drugs that belong to the following families:                1. Antineoplastic drugs        2. Chemotherapeutic agents        3. Anti-infective agents (e.g. Antimicrobial drugs, Antiparasitic agents, Antivirals)        4. Genito-urinary system drugs        5. Anti-inflammatory products        6. Analgesics        7. Musculoskeletal system acting drugs        8. Drugs acting on the blood and blood forming organs (Antihemorrhagics, Antithrombotic agents, antianemic drugs)        9. Dermatologic drugs (antifungals, antiseptic)        10. Gastrointestinal system (antiobesity, acid related disorders)        11. Metabolism drugs        12. Neurological drugs        13. Respiratory drugs including nasal drugs        14. Cardio-vascular drugs        15. Otological drugs        16. Anti-infective drugs        17. Corticosteroids drugs        18. Analgesics drugs        19. Antiparasitics drugs        20. Anasthetic Drugs        
In other cases, the topical treatment is just evolving:                21. Growth factor (e.g., for treatment of heart muscle ischemia)        22. Gene Therapy agents        
In other cases, the topically administered material has medical effect without actually being considered an active pharmaceutical ingredient:                23. Mucin        24. Hyaluronic Acid        
Besides their therapeutic effect, drugs are classified according to their chemical and physical properties and thus constitute families of compounds that, due to their common similar characteristics, fit particular drug vehicles. Some of those properties include:                Lipophilicity or hydrophilicity        Molecular weight and physical size        Diffusability through different media which is hydrophobic, hydrophilic, viscose, etc.        Solubility        
iv. Physical characteristics of internal cavities
The effectiveness of application of a topical therapeutic agent to a specific internal cavity will depend on the physical characteristics of the inner tissue of that internal cavity, in particular, characteristics such as:                Access—ease of introducing liquid or gel into the cavity        Tissue type that defines adhesiveness—ability to attach reliably and consistently polymer to the cavity tissue        Internal movement—effected by gravitational motion, stretching, peristaltic motion, etc. that cause periodical changes in the shape and volume of the cavity—pressure and volume regime        Wetness—to enable diffusion of drugs into the tissue        Degradability mechanism—flow of liquids or aqueous solutions, e.g. urine, serous or lymphatic fluids,        
The specific values of cavity characteristics require careful consideration in the development of topical drugs suitable for treatment of diseases inside these cavities.
Table 1 summarizes the different organs, types of tissue their inner lining is made of and characteristics of the surrounding medium.
TABLE 1Type ofElasticity/SystemOrganTissueMobilitypHSurroudingsDigestiveMouth/TongueMucosalVeryNeutralFlow of food and liquidsEsophagusMucosalNoneNeutralFlow of food and liquidsStomachMucosalVeryStronglyVery acidic fluids, enzimaticacidicactivityDuodenumMucosalModerateSlightlyFlow of bolus, enzymatic activityalakineSmall intestineMucosal,ModerateSlightlyFlow of bolus, enzymatic activity,ciliatedalakineabsorption of nutrientsLarge intestine MucosalModerateSlightlyFlow of fecesalakineRectumMucosalModerateSlightlyFlow of fecesalakineRespiratoryMouth/NoseMucosalNoneNeutralFlow of air and humidityLarinxMucosalModerateNeutralFlow of air and humidityEustachianMucosal,NoneNeutralPresence of air, humiditytubesciliatedPharinxMucosalModerateNeutralFlow of air and humidityThracheaMucosalNoneNeutralFlow of air and humidityLungs/AlveoliMucosalModerateNeutralFlow of air and humidityUrinaryKidneysMucosalNoneSlightlyBlood filtration, production ofacidicurineUretersMucosalNoneSlightlyFlow of urineacidicBladderMucosalVerySlightly Accumulation and evacuation ofacidicurineProstateMucosalNoneSlightly Flow of urine and semen (slightlyacidicalkaline in ejaculation)UrethraMucosalModerateSlightlyFlow of urine and semen (in theacidicmales)GenitalVas deferensMucosal,NoneNeutralFlow of seminal fluidsciliatedEpididymisMucosal,NoneNeutralFlow of seminal fluidsciliated TestesMucosalModerate NeutralProduction of seminal fluidsCoitus, flow of semen, flow ofVaginaMucosalNoneNeutralmenstrual fluidsCervixMucosalModerateNeutralFlow of semen, flow of menstrualfluidsFallopianMucosal,NoneNeutralFlow of semen, flow of menstrualtubesciliatedfluidsOvulesMucosalNoneNeutralProduction of ovaPleuraPleuralSerousModerateNeutralPleural fluidsmembranesPeritoneumPeritonealSerousModerateNeutralPerituneal fluidsmembranes
v. Chemotherapy—Anticancer Drugs
Many chemotherapy (antineoplastic) drugs used as cancer treatments bind to DNA, resulting in synthesis inhibition and strand breakage. In standard intravesical instillations, chemotherapy drugs are administered at dose concentrations of around 1 mg/ml for 1-2 hour sessions.
In the particular case of treatment of bladder cancer, the bladder tissue penetration by chemotherapy drugs—a critical parameter in treatment effectiveness—exhibits a linear relationship with the concentration of the chemotherapy drugs (see Gao X, Au J L, Badalament R A, Wientjes M G. Bladder tissue uptake of mitomycin C during intravesical therapy is linear with drug concentration in urine. Clin Cancer Res. 1998 January; 4(1):139-43)). Furthermore, chemotherapy drug penetration is 40% higher in the tumor tissue than in the adjacent normal urothelium. Gao et al demonstrated double Mitomycin C (MMC) concentration in tissue when installing 40 mg/20 ml as compared with 20 mg/20 ml MMC: human bladder tumors had a significantly higher tissue uptake of MMC than the normal bladder tissue.
The anti-tumor effect of chemotherapy drugs depends on concentration and exposure time. Schmittgen et al (see Schmittgen T D, Wientjes M G, Badalament R A, Au J L. Pharmacodynamics of mitomycin C in cultured human bladder tumors. Cancer Res. 1991 Aug. 1; 51(15):3849-56) demonstrated, both in TCC cell cultures and human bladder tumor tissue cultures, that a ten times higher concentration was needed in order to get a similar cell kill effect when exposure time to MMC was reduced from 24 hours to two hours.
The proven conclusion is that maintaining higher drug concentration for longer treatment duration will enhance the treatment efficacy.
vi. Required Properties for Topical Treatment in the Bladder and Other Internal Cavities
One approach to treatment of diseases of internal body cavities such as the bladder is topical application of a therapeutic agent entrained in a suitable matrix/mixture. The properties of the materials to be used in such a matrix/mixture must be adapted to the needed medical effect.
Important properties include:                Rheological properties (viscosity, thixotropy, G′, G″)—required for the introduction of the material into the internal cavity        Adhesion—required to coat dependably the target tissue        Flexibility—to comply with the volume and shape natural changes of the internal cavity under treatment        Dilution in aqueous solution—to enable API release and natural expelling of the material through body fluids        Mechanical properties, such as hardness, tensile strength to provide        Duration of time that the material remains in the internal cavity before it degrades        A suitable Active Pharmaceutical Ingredient (API)—the medical drug or drug derivative chosen from the families listed in section iii        Loading of drug or API in the material. For certain clinical protocol the amount and concentration of the drug or API mixed into the material have to be set to a prescribed level. The amount of therapeutic agent thus used can be significantly lower than used in regular parallel instillations and more than a single API can be loaded. So the API part of the administered material may vary from zero concentration (gel only) to 50% (e.g., for DMSO).        The ability of the matrix/mixture to release the drug in a controlled manner such that the actual drug concentration vis-à-vis the organ tissue or lining upon which the mixture is adhered will be optimal for each treatment. It is precisely the specific composition of the mixture that determines the release profile of the drug and its adsorption into the target tissue. For example, if the API is lipophilic, the addition of certain surface-active agents in given concentrations will provide for their emulsification, easier release from the drug composition and easier absorption by the internal organ lining.        Drug viability. The material is designed and tested not to reduce the viability duration of the drug or API that is mixed into it, so that the amount that is released throughout the treatment will have the optimal therapeutic effect.        
vii. Limitations of Superficial Bladder Cancer (SBC) Treatments Known in the Art
SBC is a highly-recurrent form of cancer. To lower recurrence, it is considered necessary to treat patients with a single intravesical chemotherapy instillation immediately after TUR-T.
A meta-analysis of 7 randomized trials (1,476 patients with a median follow-up of 3.4 years) has demonstrated that one chemotherapy instillation immediately after Tumor resection (TUR) decreases the relative risk of recurrence by 40% (see Sylvester R J, Oosterlinck W, van der Meijden A P. A single immediate postoperative instillation of chemotherapy decreases the risk of recurrence in patients with stage Ta T1 bladder cancer: a meta-analysis of published results of randomized clinical trials. J Urol. 2004 June; 171(6 Pt 1):2186-90). The timing of the instillation is crucial: in all studies, instillation was administered within 24 hours. A study reported that if the first instillation was not given within 24 hours, the risk of recurrence increased twofold (see Kaasinen E, Rintala E, Hellström P, Viitanen J, Juusela H, Rajala P, Korhonen H, Liukkonen T; FinnBladder Group. Factors explaining recurrence in patients undergoing chemoimmunotherapy regimens for frequently recurring superficial bladder carcinoma. Eur Urol. 2002 August; 42(2):167-74).
Following resection and first immediate treatment patients need to be stratified by their risk for tumor progression and recurrence:                Patients with low risk for disease progression/recurrence (30%)—need no further instillations.        Intermediate risk patients (40-50%)—usually receive 6 additional sessions of Mitomycin C (MMC) chemotherapy instillations.        High risk patients (20%)—are treated with 6 intravesical Bacillus Calmette-Guerin (BCG) instillations.        
The efficacy of the current standard topical chemotherapy treatment for Superficial Bladder Cancer (intravesical instillation) is limited, because there is no control on the chemotherapy concentration and the time until it is expelled. In an attempt to prolong the standard treatment to two hours, some physicians dictate behavioral conditions to reduce acidity of the bladder, to reduce the volume of urine before the instillation and instill maximal concentration of chemotherapy dissolved in minimal volume of saline.
There are several obstacles and complications known that accompany the presently used methods for coating the internal wall of the bladder (and hence for topical treatments for bladder cancer):                The mucosal membrane. One of the physiological purposes of the mucosal membrane that covers the bladder's inner wall, which is permanently soaked in urine (i.e., a watery composition), is to prevent adherence of foreign bodies to it. Therefore, any composition targeted to adhere to the internal wall of the bladder will have to overcome the difficulty of adhering to such mucosal membrane. Furthermore, since the mucosal layer is in constant contact with urine, in order to coat it, a hypothetical option would be to initially dry it. However, such an operation is not acceptable in present medical practice. Another complication stems from the membrane structure, which is composed from several cell layers where the outermost is the terminally differentiated ‘umbrella’ cells that are the urothelium most superficial layer. Regular biological adhesives, such that are used to stop bleeding (e.g. Tabotamp that is distributed by Johnson & Johnson, NJ, USA), can bond strongly through the wet surface and peel-off that delicate, outermost layer and thus damage the membrane. The achievement of a satisfactory non-damaging coating of wet, non-adherent mucosal tissue is very challenging indeed.        The bladder's natural expansion and collapse. The bladder is essentially muscular tissue and its wall is naturally highly flexible. The inner volume of a mature bladder varies greatly, from a collapsed or ‘empty’ state with a volume of 0-30 ml up to a filled bladder with a volume of up to 500-600 ml (though the bladder usually fills only up to 150-200 ml before micturition point, that is, when the individual feels the urge to urinate and indeed vacates the bladder. Therefore, providing a composition that has the capacity to adhere and conform to the bladder wall without damaging the outer layer, adapt itself to the bladder's morphology in spite of the great variance in volume and the fact that it is permanently changing its form and volume and stay adhered to it is considered an enormous challenge.        Further to the above mentioned difficulties to adhere onto a mucosal membrane, it is also highly challenging to do so while avoiding the peeling-off of the outermost layer of the membrane—due to adhering shear forces or adhesion between tissue areas. So while biological glues that can stop bleeding can also adhere through the wet mucosal layer, their rigidity compromises the integrity of the outermost layer and negates the required therapeutic effect.        The same obstacles, to even greater extent, are relevant to the treatment of the same cancer (transitional cell carcinoma) in the upper urinary tract. TCC in the upper urinary tract is a rare urological disease and has a propensity for multifocality, local recurrence, and development of metastases. Almost 5% of all urothelial neoplasms occur in the kidney and ureters. The standard treatment for patients with upper tract TCC and a normal kidney is a complete removal of the involved kidney, ureter and bladder cuff. A less-invasive treatment, namely resection of tumors followed by instillation with chemotherapy or immunotherapy, is recommended for patients with anatomic or functional solitary kidneys, bilateral upper-tract TCC, base line renal insufficiency, or inability to tolerate major surgery. Patients with a normal contralateral kidney who have small, low-grade lesions can also be reasonable candidates for this organ conserving management.         Topical immunotherapy or chemotherapy instillations for treatment of UTUC are used as primary or adjuvant treatment in order to reduce tumor recurrence. Topical instillation is performed using either infusion through a percutaneous nephrostomy tube, via a retrograde ureteral catheter, or by retrograde reflux from the bladder with an indwelling double-J stent. The main disadvantage in all these treatments is the short residual duration of the active agent in the treated area resulting in a low exposure time essential for treatment efficacy. This may be one of the reasons for the shorter average disease-free duration of upper tract TCC patients, compared to lower tract TCC patients.        Another bladder disease is overactive bladder (OAB)—when the bladder contracts suddenly without patient's control when the bladder is not full. This syndrome affects an estimated 1 in 11 adults in the United States—especially common in older adults.         Current available treatment options for OAB are: bladder training, pelvic floor exercises, drug therapy such as anti-cholinergics, capsaicin, intravesical botulinum toxin injections and in severe cases—bladder augmentation surgery.         Current oral drugs have high adverse event rate which leads to patients' intolerability. Bladder instillation with antimuscarines has been tried with lower adverse event rate, but require recurrent catheterization due to the drug relatively short half-life that reduces compliance.         Despite promising results the drawbacks to intravesical botulinum toxin injections are numerous: the cystoscopic injection requires proficiency and authorization of the physician, some degree of anesthetic administration is required, the botulinum toxin effects only the injected anatomical locations and the treatment may lead to temporary urinary retention and need for self-catheterization.        
viii. Mechanical Support and Sustained Drug Release in Minimally-Invasive Surgery
The limited number of access ports used in laparoscopic surgery may impair the ability of the surgeon to achieve adequate retraction and exposure, or to stabilize “moving targets” while operating on nonfixed organs. Current solutions include adding more ports or using a hand-assisted technique—which have the disadvantages of being more invasive, possibly creating a cumbersome situation of multiple instruments in a limited working space—or the use of temporary sutures that pass through the abdominal wall.
The current invention provides means by which the organs can be held mechanically in place by injecting the invented materials into the cavity and letting them to solidify and support the internal organs. This invented materials and method have the additional advantages of a) serving as a soothing dressing for the surgery cuts, b) contribution to healing through sustained release of anti-infection drug and analgesic drug for a therapeutically-significant duration (e.g., over 6 hours), and c) avoiding the need for further surgical or medical procedure, by natural degradation of the material and its expelling from the body.
Similar method, but with a different family of materials can be used to prevent the adhesion of tissues between organs in the treated area, which may often occur during laparoscopic surgery.
ix. Current State-of-the-Art
To the best of the inventors' knowledge, a method for treating diseases of the bladder or other inner cavities based on production of a solidified coating layer and affixing it onto the internal wall of the bladder or other cavities, followed by continuous release of the therapeutic agent(s) from the coating, remains unknown in the art.
Furthermore, the application of the substrate material such that it creates a continuous layer substantially affixed to the mucosal lining of the bladder or the outermost tissue of other internal cavity for prolonging the exposure of the drug to the targeted cells is neither trivial nor obvious to any person skilled in the art.
Compositions known in the prior art as sustained-release substrates for the treatment of bladder cancer (for example, the invention disclosed in U.S. Pat. Appl. US2006/0127420 to Chung) are lipophilic (oil-based). Given that the inner bladder wall is mucosal, essentially and permanently soaked in an aqueous medium (i.e., urine), a drug embedded in a hydrophilic medium would more effectively diffuse through the matrix/mixture and conveniently reach the bladder wall, allowing in that way an intimate, continuous contact between the drug and the bladder wall.
Thus, there remains a long-felt and unmet need for a material with the following properties: it is hydrophilic; it provides a homogeneous layer that can securely adhere to the surfaces of internal body cavities, in particular, mucosal tissue of such cavities as the bladder; it remains attached despite the natural motions of the tissue to which it is attached; it is easily applied; it is biocompatible; it provides a continuous sustained release of a therapeutic agent; the rate of release of the therapeutic agent is determined by the concentration of the agent and the rate of degradation of the material; and after the material degrades, it is excreted from the body by the body's own natural processes.